EFFECTS OF AGE/WEIGHT AND CASTRATION ON FATTY ACIDS COMPOSITION IN PORK FAT AND THE QUALITIES OF PORK AND PORK FAT IN MEISHAN X LARGE WHITE PIGS

Abstract

This study investigates the effects of age/weight and castration on the fatty acid composition and the qualities of pork and pork fat. Thirty hybrid male pigs (50% Meishan x 50% Large White) were used. Fifteen were castrated within the first two days of age and the other fifteen remained entire. At 12 weeks of age, the pigs were divided into three groups, each consisting of five castrates and five boars. Animals were fed a basic standard commercial pelleted diet for 30,60 or 90 days and then slaughtered, so that the actual age of the pigs at slaughter was 114, 144 and 174 days respectively. Parameters considered for carcass quality were carcass weight, initial pH (pH45) and ultimate (final) pH (pHu), and P2 backfat thickness. For pork and pork fat qualities, the following parameters were considered: backfat firmness, slip point, sensory attributes and adipose tissue fatty acid composition. Increasing age/weight significantly increased carcass weight and P2 backfat thickness (P<0.01) and had a greater influence on tenderness and juiciness than sex (P<0.001). Fat firmness and slip point increased significantly with increasing age/weight from 30 to 90 days (P<0.001). Increasing age/weight resulted in increased concentrations of Stearic, (C18:0) and total saturated fatty acids (SFA) (P<0.01) but significantly lowered the concentrations of linoleic acid (18:2), linolenic (18:3) and total polyunsaturated fatty acids (PUFA) (P< 0.001). Castration increased total lipid by 9.8g (P<0.01), made backfat firmer from 60 to 90 days (P<0.05), but significantly lowered abnormal odour in lean muscle (P< 0.001) and the concentration of polyunsaturated fatty acids (P<0.01). The nutritional quality index of backfat declined significantly with increasing age (P<0.01) and also in castrates than boars (P<0.05). Backfat thickness, slip point and fat firmness/hardness had good positive correlations with the major SFA (C16:0 and C18:0), C18:0/C18:2 ratio, total lipid and total SFA, but good negative correlations with the PUFAs. Both boars and castrates can produce quality pork and pork fat if they are slaughtered at suitable ages before the boars attain the threshold level for boar taint and before the castrates become excessively fat such that their meat may not appeal to health conscious consumers